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E2. Meadows Edge Memo Upsize Reimbursement411111!1114 CITY OF KALISPELL MEMORANDUM To: Doug Russell — City Manager CC: Susie Turner — Public Works Director Aimee Cooke — Finance Director From: Keith Haskins — Deputy Director PW / City Engineer Re: Upsize for Lift Station and Force Main for Meadows Edge Development Meeting Date: 2/3/2025 BACKGROUND: As development occurs in areas where additional growth is anticipated, the city has the option to participate financially via impact fee funds to oversize developer installed utilities. This is a very cost-effective approach to completing portions of future capital improvement projects which would otherwise require the city to pay the full cost for the completion of the future infrastructure project. By participating in the upsizing process, the city shares the cost of increasing infrastructure capacity beyond what the developer needs for their project. Developers remain responsible for the portion of the infrastructure that serves their development, as outlined in the extension of service policy. The city covers only the cost difference required for the upsize. This saves the city mobilization costs, removal costs, and costs to keep existing systems active (such as temporary water or bypass pumping). The costs associated with upsizing infrastructure for new developments are factored into the utility impact fee calculations. Each year, the impact fee budget includes the anticipated costs of these upsizing projects to ensure proper funding. The Meadows Edge Subdivision included the installation of a regional lift station and sewer force main as indicated in the Sanitary Sewer Facility Plan, sized and located to serve future growth. The final sizing of the lift station to serve future growth was based on a technical memorandum by the city's consultant (AE2S) titled, Kalispell On -Call Modeling Utility Modeling Task No. 3 Meadows Edge Sewer Analysis (Attachment 1). Per the memo, the wet weather flow for the regional area to be served was determined to be 358 gpm. The same tech memo determined that Meadows Edge would need the lift station sized at 157 gpm if the lift station were to only serve their development and meet City Design and Construction Standards. Therefore, the participation rate for the lift station upsize can be calculated as: • Meadows Edge = 157/358 = 44% • City of Kalispell = 100%-44% = 56% The same participation rates were used for the force main upsize from 4" needed to serve the development to 6" needed to serve the regional growth area. 201 1" Avenue E IPhone (406)758-7720 Po Box 1997 Public Works Department Fax (406)758-7831 Kalispell, MT 59903 1 1 www.kalispell.com The cost of the lift station and force main based on project bids was $504,806, as detailed in Figure 1 (and as provided in the Engineer Certified Bid Tabulation — Attachment 2), making the city's portion of the cost $282,691.36. Description Unit Quantity Unit Price Total 8" Ductile Iron Sewer Main LS 1 $ 10,512.00 $ 10,512.00 Precast Wet Well Basin LS 1 $ 60,906.00 $ 60,906.00 Lift Station Pump Package LS 1 $ 209,192.00 $ 209,192.00 Electrical and Controls LS 1 $ 61,920.00 $ 61,920.00 Backup Generator LS 1 $ 61,596.00 $ 61,596.00 6" Sewer Force Main HDPE LF 1324 $ 70.00 $ 92,680.00 6" Sewer Force Main 900 Bend EA 1 $ 500.00 $ 500.00 6" Sewer Force Main 22.50 Bend EA 2 $ 500.00 $ 1,000.00 6" Sewer Force Main 11.250 Bend EA 1 $ 500.00 $ 500.00 Connect to Existing Manhole EA 1 $ 6,000.00 $ 6,000.00 $ 504, 806.00 Meadows Edge (44%) = $ 222,114.64 City of Kalispell (56%) = $ 282,691.36 Figure 1 - Lift Station and Force Main Cost Summary (Engineer Certified Bid Tabulation Attached) This project is one of several projects that were anticipated this fiscal year and budgeted for in the sewer fund (Item 955) for sanitary sewer and lift station upsize participation. An upsized gravity sewer main is currently under construction as part of the development and will be part of a future upsize expenditure request. REQUESTED ACTION: Motion to approve the disbursement of $282,691.36 in sewer impact fee funds to Meadows Edge LLC as City participation in the upsize of the regional lift station and force main located in Meadows Edge Phase 4. Meadows Edge, LLC P.O. Box 2190 Woodland, WA 98674 FISCAL EFFECTS: Participation in this upsize was anticipated and appropriately budgeted for in FY 24/25. A summary of the budget and remaining funds is provided below. Sewer Impact Fee Line Item 955: Main & LS U size FY 24/25 Budget $1,356,633.00 Meadows Edge LS & Force Main U size $ 282,691.36 Remaining Budget $ 1,073,941.64 ALTERNATIVES: As suggested and recommended by Council. Attachments: • Kalispell On -Call Modeling Utility Modeling Task No. 3 Meadows Edge Sewer Analysis (technical memo) 0 Certified Bid Values for Lift Station and Force Main 1-17-25 vvvvvv. ae2s. Cam TECHNICAL MEMORANDUM To: Keith Haskins, PE, City Engineer City of Kalispell, MT From: Donovan Voeller, Modeling Services Coordinator AE2S Re: Kalispell On -Call Modeling Utility Modeling Task No. 3 Meadows Edge Sewer Analysis Date: January 5, 2022 BACKGROUND 1.1 Authorization, Scope, and Model Assumptions AE2S received a request from the City of Kalispell (City) to analyze the future lift station needs along the Farm to Market Rd north of Mountain Vista Way in the northwest section of town. Modeling tasks for the assignment included the following: Lift Station Sizing: o Utilize the InfoSewer (Steady State) model to determine the required capacity of the growth and development lift station to serve the Meadows Edge Subdivision Phases 3 and 4 (Development). o Utilize the steady state model to determine the buildout capacity of a Regional lift station to serve the Development as well as additional growth area to the southeast and northwest of the Development. Develop a memorandum summarizing: o Modeling assumptions and results. o Recommended forcemain size, development lift station capacity, and Regional lift capacity. o Model loading includes the following assumptions: ■ Approximately 129 single family units for Phases 3 and 4 of the development (-31 acres at 4.16 units/acre). ■ Approximately 140 acres for the growth area northwest of the development (582 units assuming there is similar density of single family dwellings). ■ Approximately 9.9 acres for the southeast area of the development (41 units assuming there is similar density of single family dwellings). Page 1 of 10 Think Big. Go Beyond. AE,,!; www.ae2s.com Technical Memorandum RE: Kalispell On -Call Modeling Utility Modeling Task No.3 Meadows Edge Sewer Analysis January 5, 2022 • Refer to Figure 1 for a general overview of the existing wastewater collection system in the vicinity of the Development as well as the potential contributing service are for the lift station analysis. Figure 1: Existing System Layout and Service Area Northwest Service Area 0 6 a Proposed Lift Station a 6 Southeast Service Area r o© a a v t` West Side r, •+,,,,.•°"" Interceptor ^ rye m a The topography of the Development Phases 3 and 4 generally flows downhill from west to east and requires a lift station in eastern end of the development. Gravity sewer through the Development will generally flow eastward to the lift station location shown in Figure 1. Page 2 of 10 Think Big. Go Beyond. AEs www.ae2s.com C:1DatalProjectslWAFS1K1Kalispell1Task 3 - Meadows Edge�TO-3 Meadows Edge Sewer Memo.docx Technical Memorandum RE: Kalispell On -Call Modeling Utility Modeling Task No.3 Meadows Edge Sewer Analysis January 5, 2022 The topography of the northwest service area generally flows downhill from west to east. Gravity sewer that would serve a majority of the northwest area could directly connect to Development Phase 3 and 4 sewers and conveyed to the proposed Regional lift station while maintaining minimum slope and bury depth. Therefore, the Regional lift should be sized to serve northwest service area. The topography of the southeast service area generally flows downhill to the northeast. Elevation data was reviewed for the potential of this area to be connected to the Regional lift station via gravity sewer. According to the elevation review, it appears to be feasible to serve a majority of the area; however, it would require some fill within the service area. The sewer will require easements need to be placed within the roadway of the Farm to Market Rd, which may not be desirable. Therefore, it is recommended that this area be served by a private lift station or pressurized system that connects to the sanitary sewer on Mountain Vista Way immediately south of growth area. Meadows Edge Phase I and 2 must be routed to the West Side Interceptor as discussed later is this memo for the sewer on Battle Ridge Dr and Triple Creek Dr. to have capacity to support the southeast service area 1.2 Previous Studies and Other Documents The following documents were identified as being relevant to evaluating the lift station area: Wastewater Facility Plan Update for Kalispell, MT dated June 2019 by AE2S (2019 WWFP0. This facility plan provides a review of model development, calibration, system evaluation, and recommended system improvements to address existing system issues as well as a master plan for buildout of the system as described therein. New Development Water and Wastewater Design Guidelines dated June 2019 (2019 Design Guidelines) . This document summarizes City water and sewer design standards for new developments. Sewershed Exhibit dated November 2021 by WGM Group. This document summarized potential service area northwest and southeast of the Development that could be included in the Regional lift station concept. 2 PERFORMANCE REQUIREMENTS 2.1 Analysis Assumptions The 2019 WWFPU and 2019 Design Guidelines established the following criteria based on model calibration. • Average annual wastewater loading factors: o Single family dwellings: 200 gallons per day per unit. o Multi -family dwellings: 160 gallons per day per unit. Page 3 of 10 Think Big. Go Beyond. nE s www.ae2s.com C:1Data lProjectsl WAFS1K1Kalispell1 Task 3 - Meadows Edge�TO-3 Meadows Edge Sewer Memo.docx Technical Memorandum RE: Kalispell On -Call Modeling Utility Modeling Task No.3 Meadows Edge Sewer Analysis January 5, 2022 • Peaking factors based on Montana Department of Environmental Quality peaking formula: 18+ V—P PHF Peaking Factor = 4+ (P = population in thousands) • Population estimated as 2.5 people per dwelling unit for the purpose of peaking factor calculation. Table 1 provides a summary of the Development and the two additional growth areas that would contribute to the Regional lift station. The summary includes the acreage, dwelling unit count, estimated average and peak flows, and peaking factors. Using the MT DEQ peaking factor formula based on 2.5 people per dwelling unit the peaking factor was calculated and varies based on the contributing population. Note that the peak flow for the Development is estimated to be 73 gallons per minute (gpm) while the peak flow for the Regional lift station is estimated to be 358 gpm. Table 1: Meadows Edge Lift Station Summary (acre) (units) (gpm) (gal/day) (gpm) Phase 3 and 4 31 129 17.9 25,800 4.1 73 Northwest Growth Area 140 582 80.8 116,400 3.7 298 Total (Regional) 171 711 98.8 142,400 3.6 358 Southeast Growth Area 10 41 5.7 8,200 4.2 24 (not served by the regional lift station) The Meadows Edge Lift Station is assumed to replace growth and development lift station 95 identified in the 2019 WWFPU. This lift station had a small service area and had a projected buildout average flow of 18 gpm and projected buildout peak flow of 75 gpm within the facility plan. The 2019 WWFPU and 2019 Design Guidelines established the following analysis criteria based on requirements from the Montana Department of Environmental Quality (DEQ), the City, and recommended industry standards. Page 4 of 10 Think Big. Go Beyond. AEs www.ae2s.com C:1DatalProjectslWAFS1K1Kalispell1Task 3 - Meadows Edge�TO-3 Meadows Edge Sewer Memo.docx Technical Memorandum RE: Kalispell On -Call Modeling Utility Modeling Task No.3 Meadows Edge Sewer Analysis January 5, 2022 • Minimum Velocity for forcemains: 0 4 ft/s (City standard) 0 3 ft/s (MT DEQ standard) • Maximum Velocity for forcemains: o 8 ft/s (City and DEQ standard) • Maximum depth for gravity sewer d/D: o < 10 inches: 0.7 o >10-15 inches: 0.73 3 MODELING SCENARIOS ANALYZED Two model scenarios were used to analyze the peak flow into the Development and Regional lift station. • 10_States_Exist. o Used to evaluate average and peak flow. o Includes allocated loading as established in the 2019 WWFPU. 10_States_Buildout. o Used to evaluate average and peak flow with the Development and Regional Service areas. 4 SYSTEM COMPONENTS IDENTIFIED The modeling scenarios were used to assess the peak flows into a lift station that would serve the Development as well as if the lift station would serve as a Regional lift station with a broader service area. Considerations was given to the following existing collection system infrastructure: • Existing 8-inch gravity sewer in Phase I of the Meadows Edge Development beginning on S Camas Ln south of Mountain Vista Way. • Existing 12-inch gravity sewer connecting Phase I and 2 of the Development to the City's collection system. The 12-inch gravity sewer runs along Three Mile Dr to Heavens Park Dr. • Impact to downstream sewer on Battle Ridge Dr and Triple Creek Dr which has known limited excess capacity. • The West Side Interceptor located downstream and southeast of the Development area. It is located at the south end of Pine Draw Ave. • Refer back to Figure 1 for a review of the existing network. Page 5 of 10 Think Big. Go Beyond. AEs www.ae2s.com C:1DatalProjectslWAFS1K1Kalispell1Task 3 - Meadows Edge�TO-3 Meadows Edge Sewer Memo.docx Technical Memorandum RE: Kalispell On -Call Modeling Utility Modeling Task No.3 Meadows Edge Sewer Analysis January 5, 2022 5 MODELING RESULTS The model was used to assess the system under peak conditions. Assessment results are discussed in further detail in the following paragraphs. Hydraulic modeling results are discussed in the following sections as they relate to lift station capacity, forcemain capacity, and gravity sewer capacity. 5.1 Hydraulic Analysis Lift Station Capacity: As previously established in Table 1, the Development lift station requires a firm pumping capacity of 73 gpm to meet peak hour flows while a Regional lift station would require a firm pumping capacity of 358 gpm to meet peak hour flows. Pumping requirements to meet forcemain velocities are discussed in the following paragraph. Forcemain Capacity The minimum size forcemain allowed by City standards is 4-inch. In order to meet the minimum velocity of 4 ft/s that the City requires the flow rate would need to be 157 gpm or more. Therefore, the minimum firm capacity for a Development lift station (serving Phase 3 and 4) would be 157 gpm. This flow exceeds the peak hour inflow but is needed to meet forcemain size and velocity requirements. The Regional lift station concept will require a 6-inch forcemain. The peak flow for the regional lift station is estimated at 358 gpm. The velocity in a 6-inch would be 4.1 ft/s which satisfies City and MT DEQ minimum velocity requirements. A 4-inch was considered, however the velocity in a 4-inch at 358 gpm exceeds the maximum velocity threshold of 8 ft/s. Gravity Sewer Results (Upstream of Meadows Edge Lift Station) Maximum flow rate allowed within an 8-inch sewer is 340 gpm as calculated using Manning's equation with n = 0.011; minimum slope = 0.004 ft/ft; and d/D = 0.7. The maximum flow and gravity sewer capacity was reviewed using the model under the peak flow conditions. There are no gravity sewer capacity concerns for sewer upstream of the lift station if the station is constructed to only serve Phases 3 and 4 of the Development. However, as described previously, the max flow into the Regional is estimated at 358 gpm. This flow rate slightly exceeds the maximum flow rate allowed for 8-inch sewer as calculated above. The sewer upstream of the Regional lift station will need to be installed a slope greater than or equal to Page 6 of 10 Think Big. Go Beyond. nE s www.ae2s.com C:1Data lProjectsl WAFS1K1Kalispell1 Task 3 - Meadows Edge�TO-3 Meadows Edge Sewer Memo.docx Technical Memorandum RE: Kalispell On -Call Modeling Utility Modeling Task No.3 Meadows Edge Sewer Analysis January 5, 2022 0.005 ft/ft or may need to be upsized to 10-inch to maintain d/D requirements at a flow rate of 358 gpm. Figure 2 shows the location of the sewer that requires steeper slope or upsizing. Figure 2: Gravity Sewer Upstream of Regional Lift Station 1: Gravity Sewer at Minimum Grade 8-Gravity Sewer at 0.5 % or 10-inch at Minimum Grade Lift Station is Gravity Sewer Results (Downstream of Meadows Edge Lift Station) Existing gravity sewer were modeled for their ability to convey the Meadows Edge Lift Station flow rate under the Development and Regional lift station concepts. The following modeling observations were made. • A lift station serving the Development (Phase 3 and 4) can utilize a 4-inch forcemain that ties into the Phase I gravity sewer. Refer to Figure 3. • A regional lift station utilizing a 6-inch forcemain must tie into the 12-inch sewer at Three Mile Dr and W Springcreek Rd. The Regional lift station has too large of flow to send through the Phase 1B 8-inch sewer when considering contributing flows from Phase 1B,2,3, 4 and the growth area. Refer to Figure 3. • Existing sewer along Battle Ridge Dr and Triple Creek Dr cannot support flow from the Development Phase 3&4 nor the Regional lift station as additional flow will cause Page 7 of 10 Think Big. Go Beyond. AEs www.ae2s.com C:1DatalProjectslWAFS1K1Kalispell1Task 3 - Meadows Edge�TO-3 Meadows Edge Sewer Memo.docx Technical Memorandum RE: Kalispell On -Call Modeling Utility Modeling Task No.3 Meadows Edge Sewer Analysis January 5, 2022 surcharging. Therefore, the 12-inch sewer must be routed from its connection to Heavens Park Dr to the West Side Interceptor as shown in Figure 3. • Transferring the 12-inch to the West Side Interceptor opens capacity for Battle Ridge Dr and Triple Creek Dr to support flow from the southeast growth area. Figure 3: Proposed System Improvements Lift Station Development Lift Station with 4-inch forcerain can connect to Phase 16 Sewer. Direct flow southward here with new sewer to the West Side Interceptor to avoid surcharging on Battle Ridge Dr and Triple Creek Dr. Regional Lift Station with 6-inch forcemain must connect to 12-inch gravity main in Three Mile Dr. . AP rvt� ,w Q O � � Page 8 of 10 Think Big. Go Beyond. Als www.ae2s.com C:1DatalPrcjectslWAFS1K1Kalispell1Task 3 - Meadows Edge�TO-3 Meadows Edge Sewer Memo.docx Technical Memorandum RE: Kalispell On -Call Modeling Utility Modeling Task No.3 Meadows Edge Sewer Analysis January 5, 2022 6 SUMMARY AND RECOMMENDATIONS: 6.1 Sizing Requirements for a Development Lift Station serving Meadows Edge Phase 3 and 4 Only Summary of modeled conditions and recommendations for a lift station that only serves Meadows Edge Phase 3&4 are as follows: • Modeled Flows: o Average Flow: 18 gpm o Peak Flow: 73 gpm ■ Based on MT DEQ peaking factor formula. Infrastructure Sizing: o Recommended Forcemain size: 4-inch o Recommended Firm Capacity: 157 gpm ■ This flow is greater than the modeled peak inflow but is required to meet minimum velocities within forcemain. ■ Velocity = 4 ft/s • (meets City requirement of 4 ft/s). • (meets MT DEQ minimum velocity of 3 ft/s). o Recommended Gravity Sewer Size (within the Development): 8-inch o Gravity Sewer Maximum Flow Depth: ■ Phase 3 and 4 Sewer: 8-inch d/D: <0.5 (meets City requirement of 0.7). • Assumes minimum grade of 0.4 percent. Phase 1B Sewer downstream of forcemain: 8-inch d/D: <0.55 • Forcemain Connection: o The forcemain can be connected to Phase I 8-inch sewer. o Flow in the 12-inch sewer must be rerouted from Three Mile Dr to the West Side Interceptor. ■ Battle Ridge Dr and Triple Creek Dr can then support flow from the southeast growth area. Page 9 of 10 Think Big. Go Beyond. nE s www.ae2s.com C:1DatalProjectslWAFS1K1Kalispell1Task 3 - Meadows Edge�TO-3 Meadows Edge Sewer Memo.docx Technical Memorandum RE: Kalispell On -Call Modeling Utility Modeling Task No.3 Meadows Edge Sewer Analysis January 5, 2022 6.2 Sizing Requirements for Regional Lift Station Summary of modeled conditions and recommendations for a regional lift station are as follows: • Modeled Flows: o Average Flow: 104 gpm o Peak Flow: 358 gpm ■ Based on MT DEQ peaking factor formula. • Infrastructure Sizing: o Recommended Forcemain Size: 6-inch o Recommended Firm Capacity: 358 gpm ■ This flow is equal to the modeled peak flow. ■ Velocity will be 4.1 ft/s in a 6-inch forcemain. • (meets City minimum velocity requirement of 4 ft/s). • (meets MT DEQ minimum velocity of 3 ft/s). o Recommended Gravity Sewer Size within Development 8-inch but consider section upstream of lift station will need to be steeper slope (or upsized to 10-inch to convey 358 gpm). o Gravity Sewer Maximum Flow Depth: ■ 8-inch d/D: =0.67 (meets City requirement of 0.7). • Assumes minimum grade of 0.5 percent. • Forcemain Connection: o The forcemain must be connected to the 12-inch at Three Mile Dr and W Springcreek Rd. o Flow in the 12-inch sewer must be rerouted from Three Mile Dr to the West Side Interceptor. ■ Battle Ridge Dr and Triple Creek Dr can then support flow from the southeast growth area. 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